Tested this on latest nightly on Linux 64bit. When I try to tear off an about:addons page a new tab is created but it is blank, and the original remains in the first window. Steps: 1. On a new session, open google.com and ctrl-tab to create a new tab 2. On the second tab go to about:addons 3. Try to tear off the tab onto its own window Expected: The about:addons tab is torn off, becomes its own window, and the original window only has google.com on it. Actual: Original window has two tabs, one with google.com and the other one with about:addons, and a new blank tab is created. I only tried on Linux, but I am able to reproduce the problem.